Amorphous copolyesters

ABSTRACT

Disclosed are amorphous copolyesters having an inherent viscosity (IV) of at least about 0.4 dL/g measured at a temperature of 25° C. at 0.25 g/dl concentration in a solvent mixture of symmetric tetrachloroethane and phenol having a weight ratio of symmetric tetrachloroethane to phenol of 2:3 comprising (1) a diacid component consisting essentially of about 90 to 100 mole percent terephthalic acid residues and 0 to about 10 mole percent isophthalic acid residues; and (2) a diol component consisting essentially of about 10 to 70 mole percent 1,4-cyclohexanedimethanol residues and about 90 to 30 mole percent neopentyl glycol residues; wherein the amorphous copolyesters comprises 100 mole percent diacid component and 100 mole percent diol component. The amorphous copolyesters are useful in the manufacture or fabrication of medical devices which have improved resistance to degradation upon exposure to lipids, as a profile produced by profile extrusion and as an injection molded article. Also, a method of melt processing the amorphous copolyester is disclosed which allows for performing a minimal drying or no drying of the copolyester prior to melt processing.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of United States ProvisionalApplication Serial No. 60/306,221 filed Jul. 18, 2001.

TECHNICAL FIELD OF THE INVENTION

[0002] This invention relates to amorphous copolyesters derived from1,4-cyclohexanedimethanol and neopentyl glycol. More particularly, thisinvention relates to such copolyesters that have a combination of uniqueproperties and to shaped articles fabricated therefrom such as profileextrusions and medical equipment.

BACKGROUND OF THE INVENTION

[0003] Amorphous copolyesters comprising terephthalic acid (T) residuesand diol residues comprising varying ratios of 1,4-cyclohexanedimethanol(CHDM) residues and ethylene glycol (EG) residues are well known in theplastics marketplace. As used herein, the abbreviation PETG refers tocopolyesters comprising terephthalic acid residues as the diacid residuecomponent and a diol residue component comprising up to 50 mole percentCHDM residues with the remainder EG residues. PCTG refers tocopolyesters comprising T residues and a diol residue componentcomprising greater than 50 mole percent CHDM residues with the remainderbeing EG residues. Copolyesters comprising T residues and diol residuescomprising about 20 to 70 mole percent CHDM residues and about 80 to 30mole percent EG residues are amorphous. The term “amorphous” as definedherein means a polyester that does not exhibit a substantial crystallinemelting point when scanned by differential scanning calorimetry (DSC) ata rate of 20° C./minute.

[0004] Amorphous copolyesters in general possess a combination ofdesirable properties for many applications. These properties includeexcellent clarity and color, toughness, ease of processing, and chemicalresistance. Accordingly, amorphous copolyesters are known to be usefulfor the manufacture of extruded sheet, packaging materials, and partsfor medical devices, etc. Application in transparent medical partsrequires resistance to craze formation and mechanical failure whenexposed to lipid and/or isopropyl alcohol (IPA) solutions. Whereasamorphous copolyesters are known in the art to have good resistance tothese chemicals and are widely applied in these applications, crazeformation occurs at high strains and is thus an area of neededimprovement. Consequently, there is an unmet need for amorphouscopolyesters that under high strains have improved resistance to lipidand IPA solutions.

[0005] There is also an important need for amorphous copolyesters thathave improved resistance to hydrolytic degradation. U.S. Pat. No.5,656,715 discloses that copolyesters containing a diol residuecomponent comprising 60 to 100 mole percent residues of one of theisomers of 1,4-cyclohexanedimethanol exhibit improved resistance tohydrolytic degradation.

[0006] Neopentyl glycol (NPG-2,2-dimethylpropane-1,3-diol) has been usedin combination with EG and terephthalic acid to form amorphouscopolyesters. However, the combination of NPG and CHDM as the diolcomponent of copolyesters has received minimal attention. Several earlyreferences disclose copolyesters comprising both CHDM and NPG residuesand terephthalic acid residues. Example 46 of U.S. Pat. No. 2,901,466describes a copolyester of unknown composition that was reported to havea crystalline melting point of 289-297° C. U.S. Pat. No. 3,592,875discloses copolyester compositions that contain both NPG and CHDMresidues with an added polyol present for branching. U.S. Pat. No.3,592,876 discloses polyester compositions that contain EG, CHDM and NPGresidues with the NPG residue level limited to up to 10 mole percent.U.S. Pat. No. 4,471,108 discloses low molecular weight polyesters someof which contain CHDM and NPG residues, but also contain amultifunctional branching agent. U.S. Pat. No. 4,520,188 describes lowmolecular weight copolyesters comprising mixtures of aliphatic andaromatic acid residues with both NPG and CHDM residues present. JapanesePatent Publication JP 3225982 B2 discloses amorphous copolyesters whichare said to be useful in the formulation of coating compositions forsteel sheet. The disclosed copolyesters comprise a diacid componentcomprising mixtures of aliphatic and aromatic acid residues and a diolcomponent comprising NPG and CHDM residues present.

SUMMARY OF THE INVENTION

[0007] We have discovered that amorphous polyesters derived fromterephthalic acid, CHDM and NPG are valuable compositions useful for themanufacture of medical devices that exhibit improved resistance todegradation upon exposure to lipids. The amorphous copolyesters providedby the present invention have an inherent viscosity (IV) of at leastabout 0.4 dL/g measured at a temperature of 25° C. at 0.25 g/dlconcentration in a solvent mixture of symmetric tetrachloroethane andphenol having a weight ratio of symmetric tetrachloroethane to phenol of2:3 and comprise:

[0008] (1) a diacid component consisting essentially of about 90 to 100mole percent terephthalic acid residues and 0 to about 10 mole percentisophthalic acid residues; and

[0009] (2) a diol component consisting essentially of about 10 to 70mole percent 1,4-cyclohexanedimethanol residues and about 90 to 30 molepercent neopentyl glycol residues;

[0010] wherein the amorphous copolyesters comprises 100 mole percentdiacid component and 100 mole percent diol component.

[0011] Another embodiment of the present invention concerns a shapedarticle such as an extruded profile or an extruded or injection moldedmedical device having improved resistance to degradation from exposureto lipids wherein the medical device is fabricated or prepared from anamorphous copolyester having an inherent viscosity (IV) of at leastabout 0.4 dL/g measured at a temperature of 25° C. at 0.25 g/dlconcentration in a solvent mixture of symmetric tetrachloroethane andphenol having a weight ratio of symmetric tetrachloroethane to phenol of2:3 and comprising:

[0012] (1) a diacid component consisting essentially of about 90 to 100mole percent terephthalic acid residues and 0 to about 10 mole percentisophthalic acid residues; and

[0013] (2) a diol component consisting essentially of about 10 to 70mole percent 1,4-cyclohexanedimethanol residues and about 90 to 30 molepercent neopentyl glycol residues;

[0014] wherein the amorphous copolyesters comprises 100 mole percentdiacid component and 100 mole percent diol component.

[0015] In still another embodiment of the present invention, a method ofmelt processing an amorphous copolyester having a moisture content priorto melt processing of 0.02 weight % or more comprises the steps of:

[0016] (a) prior to melt processing, performing a minimal drying or nodrying of the copolyester such that the copolyester has a moisturecontent of 0.02 weight % or more prior to melt processing, and

[0017] (b) melt processing the copolyester, wherein the copolyestercomprises:

[0018] (1) a diacid component consisting essentially of about 90 to 100mole percent terephthalic acid residues and 0 to about 10 mole percentisophthalic acid residues; and

[0019] (2) a diol component consisting essentially of about 10 to about70 mole percent 1,4-cyclohexanedimethanol residues and about 90 to about30 mole percent neopentyl glycol residues,

[0020] wherein the copolyester is based on 100 mole percent diacidcomponent and 100 mole percent diol component.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 shows the melt viscosity shear rate curve at 260° C. forPETG, PROVISTA™, and the amorphous copolyester of the present inventiondescribed in Example 8. FIG. 2 shows the melt viscosity shear rate curveat 260° C. for PETG, PROVISTA™, and the amorphous copolyester of thepresent invention described in Example 10.

DETAILED DESCRIPTION OF THE INVENTION

[0022] Copolyesters comprising based on terephthalic acid (T) resdiuesand, optionally up to about 10 mole percent isophthalic acid residues,1,4-cyclohexane-dimethanol (CHDM) residues, and neopentyl glycol (NPG)residues are amorphous in the approximate composition ranges of 10 to 70CHDM to 90 to 30 NPG and these unique amorphous copolyesters showsurprising improved resistance to crazing when exposed to lipids or IPA.In addition, the combination of CHDM and NPG as comonomer diols in thecopolyesters of the present invention, results in copolyester backbonesthat exhibit enhanced stability to hydrolysis for the amorphouscomposition range. The present copolyesters having sufficient molecularweight to be molding or extrusion grade plastics and based solely onCHDM and NPG as diols, are not known. In addition, it is unexpected thatthe addition of NPG to a copolyester would improve resistance to lipidsand IPA.

[0023] The amorphous copolyesters of the present invention may beprepared by conventional polymerization processes known in the art, suchas the procedures disclosed in U.S. Pat. Nos. 4,093,603 and 5,681,918.Examples of polycondensation processes useful in the present inventioninclude melt phase processes conducted with the introduction of an inertgas stream, such as nitrogen, to shift the equilibrium and advance tohigh molecular weight or the more conventional vacuum melt phasepolycondensations, at temperatures in the range of from about 240 to300° C. or higher which are practiced commercially. The terephthalic andisophthalic acid residues of the copolyesters may be derived from eitherthe dicarboxylic acids or ester-producing equivalents thereof such asesters, e.g., dimethyl terephthalate and dimethyl isophthalate, or acidhalides, e.g. acid chlorides. Although not required, conventionaladditives may be added to the copolyesters of the invention in typicalamounts. Examples of such additives include pigments, colorants,stabilizers, antioxidants, extrusion aids, slip agents, carbon black,flame retardants and mixtures thereof.

[0024] The polymerization reaction may be carried out in the presence ofone or more conventional polymerization catalysts. Typical catalysts orcatalyst systems for polyester condensation are well-known in the art.Suitable catalysts are disclosed, for Example, in U.S. Pat. Nos.4,025,492,4,136,089, 4,176,224, 4,238,593, and 4,208,527, thedisclosures of which are herein incorporated by reference. Further, R.E. Wilfong, Journal of Polymer Science, 54, 385 (1961) describes typicalcatalysts, which are useful in polyester condensation reactions.Preferred catalyst systems include Ti, Ti/P, Mn/Ti/Co/P, Mn/Ti/P,Zn/Ti/Co/P, Zn/Al. When cobalt is not used in the polycondensation,copolymerizable toners may be incorporated into the copolyesters tocontrol the color of these amorphous copolyesters so that they aresuitable for the intended applications where color may be an importantproperty. In addition to the catalysts and toners, other additives, suchas antioxidants, dyes, etc. may be used in the copolyesterifications.

[0025] The copolyesters of the invention have an inherent viscosity (IV)of at least about 0.4 dL/g, preferably about 0.5 to 1.1 dL/g, measuredat a temperature of 25° C. at 0.25 g/dl concentration in a solventmixture of symmetric tetrachloroethane and phenol having a weight ratioof symmetric tetrachloroethane to phenol of 2:3. Preferably, the diacidcomponent consists essentially of at least 95 mole percent and morepreferably 100 mole percent terephthalic acid. The diol componentpreferably consists of residues of about 30 to 70 mole percent CHDMresidues and about 70 to 30 mole percent NPG residues. The mostpreferred copolyesters have an IV of about 0.60 to 1.1 dL/g andcomprise:

[0026] (1) a diacid component consisting essentially of terephthalicacid residues; and

[0027] (2) a diol component consisting essentially of about 35 to 60mole percent 1,4-cyclohexanedimethanol residues and about 40 to 65 molepercent neopentyl glycol residues;

[0028] wherein the amorphous copolyesters comprises 100 mole percentdiacid component and 100 mole percent diol component.

[0029] The copolyesters of the invention can be molded and extrudedusing conventional melt processing techniques to produce the shapedarticle of our invention. The copolyesters are particularly useful inthe manufacture of small and intricately shaped articles such as tubingused for handling and transporting medical fluids, etc. The lipidresistance of the copolyesters of our invention under external strainrenders the copolyesters particularly useful in the manufacture ofshaped articles including medical devices such as tubes, pump housings,connectors, etc. where lipid resistance is important. Such shapedarticles manufactured from the copolyesters of this invention possessimproved resistance to degradation by medical lipid solutions such asLiposyn II 20% intraveneous fat emulsion. The improved resistance todegradation is manifested by retention of elongation to break values(retention of toughness) and significant reduction of visual crazing inmolded test bars as shown in the examples below.

[0030] The shaped articles may be produced according to conventionalthermoplastic processing procedures such as injection molding,calendaring, extrusion and rotational molding. The amorphouscopolyesters of the present invention derived from CHDM and NPG exhibitimproved hydrolytic stability at various melt temperatures. In theconversion of the copolyesters into shaped articles, the moisturecontent of the copolyester typically is reduced to less than about 0.02%prior to melt processing.

[0031] Preferably, prior to melt processing, the minimal drying isperformed by conventional methods for less than 2 hours at 60 to 100° C.For the minimal drying, a desiccant bed with forced dehumidified air at60° C. to 100° C. is preferred. Even more preferably, there is no dryingof the copolyester prior to melt processing.

[0032] The melt viscosity versus shear rate relationship in polymers isa very important property of polymeric materials. One useful meltviscosity/shear rate relationship is shear thinning. Shear thinningoccurs when the melt flow is non-Newtonian and shows a reversibledecrease in viscosity with increasing shear rate. Shear thinningcharacteristics are very important for allowing the processing ofinjection molded and extruded parts and sheets, such as profiles.Profile extrusion is an extrusion process where special dies are used toproduce articles of asymmetrical shapes. House siding, plastic tubes,channels, baseboard moldings, etc. are examples of profile extrudedparts and are referred to as profiles. Generally amorphous polymers areused in profile extrusion to avoid the shrinking that takes place duringcrystallization processes. The asymmetric nature of the products fromthis process requires special resin properties such as high meltstrength at low melt viscosities and shear thinning melt rheology. Theamorphous copolyesters of the present invention exhibit improved shearthinning behavior.

[0033] Referring to the accompanying Figure, FIG. 1 shows melt viscosityshear rate curves at 260° C. for several polymers: (1) PETG is acopolyester comprises a diacid component consisting of 100 mole percentterephthalic acid residues and a diol component consisting of 69 molepercent ethylene glycol residues and 31 mole percent CHDM residues andis commercially available as EASTAR® 6763 Copolyester from EastmanChemical Company; (2) PROVISTA™ copolyester (also available from EastmanChemical Company), which is specifically designed to shear thin byadding branching agents, has a composition similar to PETG; and (3) thecopolyester of Example 8 of the present invention. Surprisingly, Example8 exhibits a shear thinning behavior that resembles the PROVISTA™copolyester and not the PETG. Similarly, FIG. 2 shows melt viscosityshear rate curves at 260° C. for the copolyester of Example 10 whichshear thins like PROVISTA™ copolyester and not PETG copolyester. For thecurves constituting FIGS. 1 and 2, the complex viscosity was determinedby a Rheonmetrics Dynamic Analyzer (RDA II) with 25 mm diameter parallelplates, 1 mm gap and 10% strain at 260° C. The samples were dried at 60°C. for 24 hours in a vacuum oven before the frequency sweep test.

[0034] Thus, based on the shear thinning properties described in FIGS. 1and 2, another embodiment of the present invention is a profile producedby profile extrusion comprising an amorphous copolyester compositionhaving an inherent viscosity of at least 0.5 dl/g and comprising:

[0035] (1) a diacid component consisting essentially of about 90 to 100mole percent terephthalic acid residues and 0 to about 10 mole percentisophthalic acid residues; and

[0036] (2) a diol component consisting essentially of about 10 to about70 mole percent 1,4-cyclohexanedimethanol residues and about 90 to about30 mole percent neopentyl glycol residues;

[0037] wherein the amorphous copolyesters comprises 100 mole percentdiacid component and 100 mole percent diol component.

[0038] Further, another embodiment is an injection molded articlecomprising an amorphous copolyester consisting essentially of an acidcomponent of residues of at least 90 mole percent terephthalic acid anda glycol component of residues of about 10 to about 70 mole percent1,4-cyclohexanedimethanol and about 90 to about 30 mole percentneopentyl glycol, based on 100 mole percent acid component and 100 molepercent glycol component.

EXAMPLES

[0039] The following Examples are intended to illustrate, but not limit,the scope of the present invention. The inherent viscosities weremeasured at a temperature of 25° C. at 0.25 g/dl concentration in asolvent mixture of symmetric tetrachloroethane and phenol having aweight ratio of symmetric tetrachloroethane to phenol of 2:3. The 2^(nd)cycle glass transition temperatures were determined according to DSC ata heating rate of 20° C./min to a temperature of 280-300° C., quenchingin liquid nitrogen to 0° C., and then rerunning the sample and recordingthe Tg as the 2^(nd) cycle glass transition temperature. Finalcopolyester compositions were determined by proton NMR analysis on a 600MHz JEOL instrument.

Example 1

[0040] A copolyester comprising a diacid component consisting of 100mole percent terephthalic acid residues and a diol component consistingof 66 mole percent CHDM residues and 34 mole percent NPG residues(hereinafter referenced as 100T/85CHDM/15NPG) was prepared. Dimethylterephthalate (DMT; 77.6 g, 0.4 mole), NPG (28.91 g, 0.28 moles), CHDM(46.37 g, 0.32 moles), and 1.49 ml of a solution containing 15 g oftitanium tetraisopropoxide in 250 ml of n-butanol were added to a 500 mlsingle-neck, round-bottom flask. The flask was immersed in a Belmontmetal bath that was pre-heated to 200° C. Immediately after the flaskwas immersed the temperature set point was increased to 220° C., andheld for 1 hour. After the hour at 220° C. the temperature was increasedto 260° C., and held for 30 minutes. After this time the theoreticalamount of methanol was collected. The pressure in the flask then wasreduced from atmospheric to 0.5 Torr. When the pressure had been reducedto 0.5 Torr the temperature set point was raised to 280° C. Stirring wasreduced as the viscosity increased until a stir rate of 15 revolutionsper minute (rpm) was obtained. The vacuum was discontinued and nitrogenwas bled into the flask. The polymer was allowed to solidify by coolingto a temperature below Tg, removed from the flask and ground to passthrough a 3 mm screen. The inherent viscosity of the polymer was 0.895dL/g. The polymer had a 2^(nd) cycle Tg of 87.82° C. Compositionalanalysis (by NMR) showed the diol component of the copolyester consistedof 66.1 mole percent CHDM residues and 33.9 mole percent NPG residues.

Example 2

[0041] A copolyester having the composition 100T/61CHDM/39NPG wasprepared. DMT (77.60 g, 0.40 moles), NPG 33.70 grams (0.33 moles) ofNPG, 39.74 grams (0.28 moles) of CHDM, and 1.49 ml of a solutioncontaining 15 grams of titanium tetraisopropoxide in 250 ml of n-butanolwere added to a 500 ml single neck round bottom flask and reacted andpolymerized according to the procedure described in Example 1. Theinherent viscosity of the polymer was 0.930 dL/g. The polymer had a2^(nd) cycle Tg of 86.70° C. with no crystalline melting point observed,and compositional analysis showed that the diol component of thecopolyester consisted of 61.4 mole percent CHDM residues and 38.6 molepercent NPG residues.

Example 3

[0042] A copolyester having the composition 100T/56CHDM/44NPG wasprepared. DMT (77.6 g, 0.40 moles), NPG (38.48 g, 0.37 moles), CHDM(33.12 g, 0.23 moles), and 1.47 ml of a solution containing 15 g oftitanium tetraisopropoxide in 250 ml of n-butanol were added to a 500ml, single-neck, round-bottom flask and reacted and polymerizedaccording to the procedure described in Example 1. The inherentviscosity of the polymer was 0.938 dL/g. The polymer had a 2^(nd) cycleTg of 85.90° C. with no crystalline melting point observed, andcompositional analysis showed that the diol component of the copolyesterconsisted of 55.8 mole percent CHDM and 44.2 mole percent NPG residues.

Example 4

[0043] A copolyester having the composition 100T/45CHDM/55NPG wasprepared. DMT (77.60 g, 0.4 moles), NPG (43.26 g, 0.42 moles), CHDM(26.50 g, 0.18 moles), and 1.44 ml of a solution containing 15 g oftitanium tetraisopropoxide in 250 ml of n-butanol were added to a 500 mlsingle neck round bottom flask and reacted and polymerized according tothe procedure described in Example 1. The inherent viscosity of thepolymer was 0.897 dL/g. The polymer had a 2^(nd) cycle Tg of 83.66° C.with no crystalline melting point observed, and compositional analysisshowed the diol component of the copolyester consisted of 44.7 molepercent CHDM and 55.3 mole percent NPG residues.

Example 5

[0044] A copolyester having the composition 100T/32CHDM/68NPG wasprepared. DMT (77.60 g, 0.4 moles), NPG (48.05 g, 0.46 moles), CHDM(19.87 g, 0.14 moles), and 1.42 ml of a solution containing 15 g oftitanium tetraisopropoxide in 250 ml of n-butanol were added to a 500 mlsingle neck round bottom flask and reacted and polymerized according tothe procedure described in Example 1. The inherent viscosity of thepolymer was 1.143 dL/g. The polymer had a 2^(nd) cycle Tg of 82.43° C.with no crystalline melting point observed, and compositional analysisshowed the diol component of the copolyester consisted of 32.3 molepercent CHDM and 67.7 mole percent NPG residues.

Example 6

[0045] A copolyester having the composition 100T/21CHDM/79NPG wasprepared. DMT (77.60 g, 0.4 moles), NPG (52.83 g, 0.51 moles), CHDM(13.25 g, 0.09 moles), and 1.40 ml of a solution containing 15 g oftitanium tetraisopropoxide in 250 ml of n-butanol were added to a 500 mlsingle neck round bottom flask and reacted and polymerized according tothe procedure described in Example 1. The inherent viscosity of thepolymer was 0.925 dL/g. The polymer had a 2^(nd) cycle Tg of 80.30° C.with no crystalline melting point observed, and compositional analysisshowed the diol component of the copolyester consisted of 21.4 molepercent CHDM and 78.6 mole percent NPG residues.

Example 7

[0046] A copolyester having the composition 100T/15CHDM/85NPG wasprepared. DMT (77.60 9, 0.4 moles), NPG (57.62 g, 0.55 moles), CHDM(6.62 g, 0.05 moles), and 1.37 ml of a solution containing 15 g oftitanium tetraisopropoxide in 250 ml of n-butanol were added to a 500 mlsingle neck round bottom flask and reacted and polymerized according tothe procedure described in Example 1. The inherent viscosity of thepolymer was 0.863 dL/g. The polymer had a 2^(nd) cycle Tg of 77.78° C.with no crystalline melting point observed, and compositional analysisshowed the diol component of the copolyester consisted of 14.6 molepercent CHDM and 85.4 mole percent NPG residues.

Example 8

[0047] A copolyester having the composition 100T/67CHDM/33NPG wasmanufactured in a batch pilot plant reactor. DMT (10.215 kg, 22.5pounds), NPG (4.495 kg, 9.9 pounds), CHDM (5.153 kg, 11.35 pounds), and53.4 g of a solution of titanium isopropoxide in n-butanol were chargedinto a 68.13 liter (18-gallon) batch reactor with intermeshing spiralagitators and a distillation column. The agitators were operated forwardfor 50 minutes and then reversed for 10 minutes. The internaltemperature was increased to 200° C. and held for 2 hours. Thetemperature then was increased to 260° C. and held for 30 minutes. Atthis time, the weight of distillate was recorded and the temperature wasincreased to 280° C. Upon reaching 280° C. the weight of distillateagain was recorded. The agitator was changed to switch directions every6 minutes, and vacuum was applied at a rate of 13 Torr/minute until fullvacuum (0.5 Torr) was reached. The polymerization mixture wasmainatained for 25 minutes at 45 rpm, and then maintained for 15 minutesat 10 rpm. The copolyester thus obtained then was immediately extrudedand chopped into pellets. The polymer had an inherent viscosity of 0.791dL/g, and a 2^(nd) cycle Tg of 87.48° C. with no crystalline meltingpoint observed. Compositional analysis (by NMR) showed the diolcomponent of the copolyester consisted of 67.4 mole percent CHDMresidues and 32.6 mole percent NPG residues. The color values, using theCIE lab color system, were as follows: L* 82.28, a* −0.44, b* 3.80.

Example 9

[0048] A copolyester having the composition 100T/45CHDM/55NPG wasproduced in a batch pilot plant reactor. DMT (10.669 kg, 23.5 pounds),NPG (6.220 kg, 13.7 pounds), CHDM (3.223 kg, 7.1 pounds), and 53.4 g ofa solution of titanium isopropoxide in n-butanol were charged into a68.13 liter (18-gallon) batch reactor with intermeshing spiral agitatorsand a distillation column. After charging the raw materials, themanufacturing procedure described in Example 10 was repeated. Theresulting polymer had an inherent viscosity of 0.844 dL/g, and a 2^(nd)cycle Tg of 84.08° C. with no crystalline melting point observed.Compositional analysis (by NMR) showed the diol component of thecopolyester consisted 45.4 mole percent CHDM residues and 54.6 molepercent NPG residues. The color values were as follows: L* 83.19, a*−0.27, b* 3.97.

Example 10

[0049] Example 9 was repeated except that the polycondensation wasmodified to produce a copolyester having a lower IV. After reaching fullvacuum (0.5 Torr), the agitator was held at 25 rpm for only 30 minutes,and then held for 15 minutes at 10 rpm. The copolyester polymer then wasimmediately extruded and chopped into pellets. The copolyester polymerhad an inherent viscosity of 0.713 dL/g, and a 2^(nd) cycle Tg of 83.41°C. with no crystalline melting point observed. Compositional analysis(by NMR) showed the diol component of the copolyester consisted of 44.1mole percent CHDM and 55.9 mole percent NPG. The color values were asfollows:

[0050] L* 82.79, a* −0.40, b* 3.15.

[0051] The resistance of the following amorphous copolyesters to attackor degradation by lipid solutions was evaluated:

[0052] Copolyester I: PETG 6763, a commercially-available amorphouspolyester wherein the diacid component consists of 100 mole percentterephthalic acid residues and the diol component consisting of about 69mole percent EG residues and 31 mole percent CHDM residues; IV=0.71.

[0053] Copolyester II: PCTG 5445, a commercially-available amorphouspolyester wherein the diacid component consists of 100 mole percentterephthalic acid residues and the diol component consisting of about 38mole percent EG residues and 62 mole percent CHDM residues; IV=0.72.

[0054] Copolyester III: Amorphous copolyester of Example 8.

[0055] Copolyester IV: Amorphous copolyester of Example 9.

[0056] Standard tensile test bars (ASTM-D638) of each of thecopolyesters I, II, III, and IV were prepared by injection molding. Thebars were placed on three-point-bend strain rigs at fixed strains of 0,0.5, 1.5 and 2.7% while simultaneously being exposed to Liposyn II 20%intravenous fat emulsion (lipid solution) for 72 hours. Exposure to thelipid solution was accomplished by placing a 2.54 mm×1.77 mm (1 inch×0.5inch) patch of filter paper over the center of the bar and saturatingthe patch with the lipid solution initially and then rewetting severaltimes a day. The treated bars were then subjected to tensile testingaccording to ASTM D638. The results of these tensile tests are shown inTable I wherein the values given for Condition Strain, Yield Strain, andElongation at Break are percentages. Yield Stress and Break Stress aregiven in megapascals. Each test bar was inspected before and after theevaluation and given a rating of A=no change, B=slightly crazed,C=moderately crazed, and D=severly crazed. Similar resistance tests wererun with IPA instead of lipid, with these results shown in Table IIwherein the values are the same as those for Table I. The controlrepresents samples prior to contact with lipid solution. An inspectionof Tables I and II clearly shows that the amorphous copolyester of thepresent invention exhibit better overall performance than thecorresponding commercial amorphous copolyester I and II. The superiorperformance is manifested, in general, by the maintenance of asatisfactory appearance and the maintenance of high elongation to breakafter exposure to the lipid while under strain. TABLE I Condition YieldElongation Yield Break Copolyester Strain Strain to Break Stress StressAppearance I Control 5.3 167 48.6 29.2 I 0 5.3 65.4 51.1 25.5 A I 0.55.3 63.2 50.5 25.1 A I 1.5 5.3 40 51.5 25.2 D I 2.7 5.2 51.3 49.8 25.9 BII Control 4.7 285 43.4 40.7 II 0 — — — — — II 0.5 4.9 289.5 46.7 43.8 AII 1.5 4.9 296.0 46.8 43.3 A II 2.7 — 6.9 — 29.5 D III Control 5.7 178.943.8 46.8 III 0 5.3 154.9 45.1 43.1 A III 0.5 5.3 148.3 45 41.7 A III1.5 5.4 137.7 45.6 40.9 C III 2.7 5.5 140.5 44.9 42.1 B IV Control 5.3134.1 47.4 42.9 IV 0 5 102.9 48.4 36.4 A IV 0.5 5.1 99.6 48.8 37.9 A IV1.5 5.2 24.7 49 36.6 C IV 2.7 5.2 18.1 48 36.9 C

[0057] TABLE II Condition Yield Elongation Yield Break CopolyesterStrain Strain to Break Stress Stress Appearance I Control 5.3 167 48.629.2 I 0 5.3 79 50.5 25.5 A I 0.5 5.3 36.7 50.3 25.2 C I 1.5 5.3 61.745.6 25.1 C I 2.7 7 26.6 41.1 25.9 D II Control 4.7 285 43.4 40.7 II 0 —— — — — II 0.5 5 287.7 46.3 43.5 D II 1.5 5.1 296.0 38.1 40.2 D II 2.77.3 6.9 33.2 39.5 D III Control 5.7 178.9 43.8 46.8 III 0 5.1 161 45.144.7 A III 0.5 5.2 159.4 44.8 43.8 B III 1.5 5.6 125 44.7 38.9 C III 2.75.7 150 42.1 42.9 D IV Control 5.3 134.1 47.4 42.9 IV 0 5.1 114.9 48.138.1 A IV 0.5 5.1 104.5 48.3 36.9 B IV 1.5 4.3 4.3 42.5 42.5 C IV 2.75.2 5.2 36.4 36.4 D

Example 11

[0058] A copolyester having the composition 100T/64CHDM/36NPG wasproduced in a batch pilot plant reactor. DMT (10.215 kg, 22.5 pounds),NPG (4.495 kg, 9.9 pounds), CHDM (5.153 kg, 11.35 pounds), and 53.4grams of a solution of titanium isopropoxide in n-butanol were chargedinto a 68.13 liter (18-gallon) batch reactor with intermeshing spiralagitators and a distillation column. The agitator was operated forwardfor 50 minutes and then reversed for 10 minutes. The internaltemperature was increased to 200° C. and held for 2 hours. Thetemperature was then increased to 260° C. and maintained for 30 minutes.After this, the weight of distillate was recorded and the temperaturewas increased to 280° C. Upon reaching 280° C. the weight of distillatewas again recorded. The agitator was changed to switch directions every6 minutes, and vacuum was applied at 13 Torr/minute until full vacuum(0.5 Torr) was reached and held for 45 minutes at 25 rpm. Thecopolyester polymer obtained then was immediately extruded, and choppedinto pellets. The polymer had an inherent viscosity of 0.678 dL/g.Compositional analysis (by NMR) showed the diol component of thecopolyester consisted of 63.9 mole percent CHDM residues and 36.1 molepercent NPG residues. The color values were as follows: L* 82.58, a*−0.66, b* 4.76.

Example 12

[0059] A copolyester having the composition 100T/38CHDM/62NPG wasproduced in a batch pilot plant reactor. DMT (10.669 kg, 23.5 pounds),NPG (6.220, 13.7 pounds), CHDM (3.223, 7.1 pounds), and 53.4 grams of asolution of titanium isopropoxide in n-butanol were charged into a 68.13liter (18-gallon) batch reactor with intermeshing spiral agitators and adistillation column. The agitator was operated forward for 50 minutesand then reversed for 10 minutes. The internal temperature was increasedto 200° C. and maintained for 2 hours. The temperature was thenincreased to 260° C. and maintained for 30 minutes. After this, theweight of distillate was recorded and the temperature was increased to280° C. Upon reaching 280° C. the weight of distillate was againrecorded. The agitator was changed to switch directions every 6 minutes,and vacuum was applied at 13 Torr/minute until full vacuum (0.5 Torr)was reached and maintained for 45 minutes at 25 rpm. The copolyesterpolymer obtained then was immediately extruded and chopped into pellets.The polymer had an inherent viscosity of 0.692. Compositional analysis(by NMR) showed the diol component of the copolyester contained 38.1mole percent CHDM residues and 61.9 mole percent NPG residues. The colorvalues were as follows: L* 83.04, a* −0.39, b* 4.60.

[0060] The hydrolytic stability of the following amorphous copolyesterpolymers was compared:

[0061] Polymers I and II: Same as Copolyesters I and II defined above.

[0062] Polymer V: Copolyester of Example 11

[0063] Polymer IV: Copolyester of Example 12

[0064] The procedure used in determining loss in molecular weight as aresult of hydrolysis involved placing a sample of the copolyester intothe barrel of a capillary rheometer and then heating to either 250° C.or 280° C. and holding for the specified time. The sample was removed,after this treatment, and the molecular weight was determined bystandard size exclusion chromatography. The molecular weight loss wascalculated from the equation 1−M_(w)/M_(o) where M_(w) is the molecularweight after treatment and M_(o) is the original molecular weight. Thehigher the number the greater the weight loss. The values listed in the“hydrolysis” rows are undried samples, while those listed in the“thermal” rows refer to samples dried at 60° C. for 48 hours at a vacuumof approximately 5 Torr. The results are shown in Table III. TABLE IIIMolecular Weight Loss Melt Melt Polymer Polymer Polymer Polymer TempTime I II V VI Hydrolysis 250 5 0.24 0.1 0.05 0.05 Hydrolysis 250 7 0.320.15 0.05 0.02 Hydrolysis 250 10 0.43 0.22 0.07 0.01 Hydrolysis 250 150.57 0.28 0.11 0.05 Thermal 250 5 0.02 0.02 0.08 0 Thermal 250 7 0.030.01 0.08 0.08 Thermal 250 10 0.02 0.02 0.12 0.05 Thermal 250 15 0.020.03 0.09 0.07 Hydrolysis 280 5 0.47 0.24 0.07 0 Hydrolysis 280 7 0.610.36 0.07 0.02 Hydrolysis 280 10 0.68 0.44 0.07 0.03 Hydrolysis 280 150.67 0.57 0.15 0.07 Thermal 280 5 0.07 0.08 0.13 0.1 Thermal 280 7 0.070.07 0.16 0.13 Thermal 280 10 0.06 0.06 0.2 0.16 Thermal 280 15 0.1 0.080.22 0.19

[0065] The invention has been described in detail with particularreference to preferred embodiments thereof, but it will be understoodthat variations and modifications can be effected within the spirit andscope of the invention.

We claim:
 1. An amorphous copolyester having an inherent viscosity (IV)of at least about 0.4 dL/g measured at a temperature of 25° C. at 0.25g/dl concentration in a solvent mixture of symmetric tetrachloroethaneand phenol having a weight ratio of symmetric tetrachloroethane tophenol of 2:3 comprising: (1) a diacid component consisting essentiallyof about 90 to 100 mole percent terephthalic acid residues and 0 toabout 10 mole percent isophthalic acid residues; and (2) a diolcomponent consisting essentially of about 10 to 70 mole percent1,4-cyclohexanedimethanol residues and about 90 to 30 mole percentneopentyl glycol residues; wherein the amorphous copolyesters comprises100 mole percent diacid component and 100 mole percent diol component.2. The amorphous copolyester of claim 1 wherein the diacid componentconsists essentially of at least 95 mole percent terephthalic acidresidues.
 3. The amorphous copolyester of claim 1 wherein the diacidcomponent consists essentially of 100 mole percent terephthalic acidresidues.
 4. The amorphous copolyester of claim 1 wherein the diolcomponent consists essentially of about 30 to 70 mole percent1,4-cyclohexanedimethanol residues and about 70 to 30 mole percentneopentyl glycol residues.
 5. The amorphous copolyester of claim 1wherein the diol component consists essentially of about 35 to 60 molepercent 1,4-cyclohexanedimethanol residues and about 40 to 65 molepercent neopentyl glycol residues.
 6. An amorphous copolyester having aninherent viscosity (IV) of about 0.6 to 1.1 dL/g measured at atemperature of 25° C. at 0.25 g/dl concentration in a solvent mixture ofsymmetric tetrachloroethane and phenol having a weight ratio ofsymmetric tetrachloroethane to phenol of 2:3 comprising: (1) a diacidcomponent consisting essentially of terephthalic acid residues; and (2)a diol component consisting essentially of about 35 to 60 mole percent1,4-cyclohexanedimethanol residues and about 40 to 65 mole percentneopentyl glycol residues; wherein the amorphous copolyesters comprises100 mole percent diacid component and 100 mole percent diol component.7. A shaped article having improved resistance to degradation fromexposure to lipids wherein the shaped article is fabricated from anamorphous copolyester having an inherent viscosity (IV) of at leastabout 0.4 dL/g measured at a temperature of 25° C. at 0.25 g/dlconcentration in a solvent mixture of symmetric tetrachloroethane andphenol having a weight ratio of symmetric tetrachloroethane to phenol of2:3 and comprising: (1) a diacid component consisting essentially ofabout 90 to 100 mole percent terephthalic acid residues and 0 to about10 mole percent isophthalic acid residues; and (2) a diol componentconsisting essentially of about 10 to 70 mole percent1,4-cyclohexanedimethanol residues and about 90 to 30 mole percentneopentyl glycol residues; wherein the amorphous copolyesters comprises100 mole percent diacid component and 100 mole percent diol component.8. The shaped article of claim 7 wherein the diacid component consistsessentially of at least 95 mole percent terephthalic acid residues. 9.The shaped article of claim 7 wherein the diacid component consistsessentially of 100 mole percent terephthalic acid residues.
 10. Theshaped article of claim 7 wherein the diol component of the amorphouscopolyester consists essentially of about 30 to 70 mole percent1,4-cyclohexane-dimethanol residues and about 70 to 30 mole percentneopentyl glycol residues.
 11. The shaped article of claim 7 wherein thediol component of the amorphous copolyester consists essentially ofabout 35 to 60 mole percent 1,4-cyclohexane-dimethanol residues andabout 40 to 65 mole percent neopentyl glycol residues.
 12. The shapedarticle of claim 11 wherein the diacid component consists essentially ofat least 95 mole percent terephthalic acid residues.
 13. The shapedarticle of claim 11 wherein the diacid component consists essentially of100 mole percent terephthalic acid.
 14. The shaped article of claim 7which is transparent medical device.
 15. The medical device of claim 14which is in the shape of a tube.
 16. The medical device of claim 14which is in the shape of a connector.
 17. The medical device of claim 14which is in the shape of a pump housing.
 18. A medical article forcontacting solutions containing lipids, the article fabricated from anamorphous copolyester having an inherent viscosity (IV) of at leastabout 0.4 dL/g measured at a temperature of 25° C. at 0.25 g/dlconcentration in a solvent mixture of symmetric tetrachloroethane andphenol having a weight ratio of symmetric tetrachloroethane to phenol of2:3 comprising: (1) a diacid component consisting essentially of about90 to 100 mole percent terephthalic acid residues and 0 to about 10 molepercent isophthalic acid residues; and (2) a diol component consistingessentially of about 10 to about 70 mole percent1,4-cyclohexanedimethanol residues and about 90 to about 30 mole percentneopentyl glycol residues; wherein the amorphous copolyesters comprises100 mole percent diacid component and 100 mole percent diol component.19. The medical article of claim 18 wherein the diacid componentconsists essentially of at least 95 mole percent terephthalic acidresidues.
 20. The medical article of claim 18 wherein the diacidcomponent consists essentially of 100 mole percent terephthalic acidresidues.
 21. A medical article for contacting solutions containinglipids, the article fabricated from an amorphous copolyester having aninherent viscosity (IV) of about 0.5 to 1.1 dL/g measured at atemperature of 25° C. at 0.25 g/dl concentration in a solvent mixture ofsymmetric tetrachloroethane and phenol having a weight ratio ofsymmetric tetrachloroethane to phenol of 2:3 comprising: (1) a diacidcomponent consisting essentially of terephthalic acid residues; and (2)a diol component consisting essentially of about 30 to 70 mole percent1,4-cyclohexanedimethanol residues and about 70 to 30 mole percentneopentyl glycol residues; wherein the amorphous copolyesters comprises100 mole percent diacid component and 100 mole percent diol component.22. The medical article of claim 21 wherein the article is a tube,connector or pump housing.
 23. A method of melt processing an amorphouscopolyester having a moisture content prior to melt processing of 0.02weight % or more comprising: (a) prior to melt processing, performing aminimal drying or no drying of the copolyester such that the copolyesterhas a moisture content of 0.02 weight % or more prior to meltprocessing, and (b) melt processing the copolyester, wherein thecopolyester consists essentially of an acid component of residues of atleast 90 mole percent terephthalic acid and a diol component consistingessentially of about 30 to about 70 mole percent1,4-cyclohexanedimethanol residues and about 70 to about 30 mole percentneopentyl glycol residues, based on 100 mole percent acid component and100 mole percent glycol component.
 25. The method of claim 24 whereinthe diol component consists essentially of about 30 to less than 70 molepercent 1,4-cyclohexanedimethanol residues and about 70 to 30 molepercent neopentyl glycol residues.
 26. The method of claim 24 whereinthe acid component has residues of at least 95 mole percent terephthalicacid.
 27. The method of claim 24 wherein the acid component has residuesof 100 mole percent terephthalic acid.
 28. The method of claim 24wherein prior to melt processing, the minimal drying is performed,wherein the minimal drying is by conventional methods for less than 2hours at 60 to 100° C.
 29. The method of claim 24 wherein prior to meltprocessing, the minimal drying is performed, wherein the minimal dryinguses a desiccant bed with forced dehumidified air at 60° C. to 100° C.30. The method of claim 24 wherein no drying of the copolyester isperformed prior to melt processing.
 31. A profile produced by profileextrusion comprising the amorphous copolyester of claim
 1. 32. Aninjection molded article comprising the amorphous copolyester of claim1.